The present invention relates to a method for sampling of milk in a milking machine and a milking machine. The milking machine comprises teat cups, a milk receiver to which vacuum from a vacuum supply draws milk from the teat cups, and a milk sampling arrangement which comprises an agitation device configured to provide a stirring process of the milk in the milk receiver, a milk sample device configured to extract a milk sample from the milk in the milk receiver, and an outlet valve device configured to control the milk flow out of the milk receiver.
Mastitis is a common and expensive illness among dairy cattle. A measure for detecting mastitis is the somatic cell count in the milk produced. However, the increase in somatic cell count which indicates subclinical mastitis may be rather small, e.g. 5-10% in milk from an infected udder quarter. This corresponds to an increase of only 1-2% if milk from the whole udder is analyzed. Determination of such a small increase requires very high accuracy, especially since the somatic cell count anyhow varies over time.
Untreated milk stratifies into layers due to the different density of the substances included in the milk. An upper layer of the untreated milk for example includes a much higher fat content than the lower layers. In order to increase the accuracy of milk samples, it is known to provide receivers with a motor-driven stirrer or the like which agitates the milk in the milk receiver before a milk sample is taken. It is also known to supply air to the milk receiver in order to agitate the milk and provide a substantially homogenous distribution of the substances in the milk receiver before a milk sample is taken. However, all kinds of mechanical treatment of milk increase the content of free fatty acids (FFA) in the milk. A too high content of free fatty acids may e.g. give the milk a rancid taste.
WO 2013/032397 shows a milking arrangement comprising an end unit provided with a motor-driven rotary agitator which provides a stirring movement of the milk collected in the end unit in order to obtain a homogenous distribution of the included substances in the milk. A sampling device takes milk samples of the mixed milk. The sampling device comprises an inlet line extracting milk from an outlet line of the end unit or directly from the end unit.
WO 93/25871 shows a meter for measuring the quantity of milk. Milk samples are collected in a milk sample reservoir on discharge of weighed discrete quantities of milk from the weighing container. There are agitating means for agitating and mixing the milk samples when they have been collected in the milk sample reservoir.